The nose gear does, in fact, take less loading than the main gear. If you imagine the plane with nose gear and main gear and centre of gravity marked, you will see that the CG is very close to the main gear. (Have a look at all the pics in the database of planes that tipped over and sit on their tails, after cargo has been unloaded properly))
If you take moments about the CG (i.e. you take times ), the Moment of the front gear has to be the same as the moment of the rear gear. As the distance is much much longer, the force is much much less. That is why less strength is needed in the front gear.
There are, of course, exceptions. Take old double-deckers or the B52 as example. Here, the moment arms are distributed differently.